Скачать или смотреть Setting Up a Simple ActiveMQ Artemis Cluster on Docker Swarm

Learn how to create a robust ActiveMQ Artemis cluster with two brokers in a `Docker Swarm` environment using a straightforward step-by-step guide.
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Setting Up a Simple ActiveMQ Artemis Cluster on Docker Swarm

Creating a robust messaging system is crucial for applications that require high throughput and reliability. ActiveMQ Artemis is a great choice for this purpose, especially when clustered for fault tolerance and load balancing. In this post, we will guide you through the process of setting up a simple cluster of two ActiveMQ Artemis brokers within a Docker Swarm environment.

The Challenge

You might encounter issues while trying to establish a cluster, particularly with broker connectivity. This is often due to incorrect configurations, especially in network settings. Our aim is to address the most common mistakes when configuring the brokers to enable seamless communication.

The Configuration Structure

Let's take a look at the provided stack configuration:

[[See Video to Reveal this Text or Code Snippet]]

Key Configuration Points

Cluster Network: Ensure you have set up an overlay network named artemis-cluster-network. This is essential for the brokers to communicate.

Broker Configurations: Each broker has its own configuration file where you define connectors and acceptors.

Connector Configuration

In both broker configuration files, you'll find sections defining connectors. You must ensure the netty-connector does not use 0.0.0.0 for its address. Instead, specify the actual IP address or hostname that the broker should use for accepting incoming connections.

Important Settings to Adjust

Change 0.0.0.0 to Actual Hostnames/IPs:
This is crucial because 0.0.0.0 serves as a wildcard address indicating all IPs on the local machine. However, in a clustered environment, it does not convey meaningful networking information to your other broker nodes.

Solution to Your Problem

The problem you're facing, where nothing happens and no meaningful logs are generated, can often be traced back to the misuse of 0.0.0.0 in the connector configuration. Here’s how to rectify this:

Update Connector Address: Instead of tcp://0.0.0.0:61616, replace it with the actual IP of the host machine or the hostname that the broker listens to.

Broker Communications: Since the brokers need to reference each other, ensure they utilize valid and resolvable addresses.

Adjust JGroups or UDP Settings: If trying to leverage multicast discovery or JGroups for discovery, be mindful that Docker Swarm’s overlay network can present challenges. Instead, consider manual cluster discovery by specifying the exact brokers.

Additional Tips

Testing Connections: After the changes, run your setup again and keep an eye on the logs for any connection attempts or errors.

Using Tools like Fiddler: When utilizing tools for HTTP inspection, ensure that hostname resolutions reflect actual broker addresses.

Conclusion

By following the points laid out in this post, you should be well on your way to establishing a functional ActiveMQ Artemis cluster within a Docker Swarm environment. Always remember to check your service configurations, especially around network connectivity, to avoid any communication black holes!

With proper configurations, you'll find yourself enjoying all the robust capabilities that ActiveMQ Artemis has to offer.